BoatsAlpa Yachts 21

Alpa Yachts 21

Masthead Sloop · Fin w/transom Hung Rudder · First built 1976

A nimble 6.48-metre masthead sloop with a high sail-area-to-displacement ratio for responsive light-air performance

Designed by Sparkman & Stephens.

LOA
Beam
Draft (max)
Displacement
Ballast
Hull type
Fin w/transom Hung Rudder

Is it for you?

Character

Where this design lands on the numbers a shopper trusts — read straight from her own ratios.

TrailerableBeam 2.49 m — inside the 2.55 m no-permit tow width across most of Europe, and the 2.59 m US and Canadian limit. About 1,301 kg of hull, so roughly 1,900 kg on a trailer: check that against your own towing rating.
LivelySea-kindly

Her moderate displacement on a beamy beam gives 14 — a quick, lively motion that feels every wave.

Comfort ratio 14
CoastalBluewater

2.30 — right around the 2.0 line, the edge between coastal and offshore.

Capsize screening 2.30
LightHeavy

199 — moderately heavy for her waterline, a balanced cruising weight.

Displacement / length 199
EasygoingPowered-up

19.5 — plenty of sail for her weight; lively and quick to respond.

Sail area / displacement 19.5
TenderStiff

28% of her weight is ballast — on the tender side; she'll heel readily and want a reef sooner.

Ballast 28%

Powered-up and quick to accelerate — this one likes to sail.

The record

Full specifications

The complete reference set — tap any figure to switch between metric and imperial.

Dimensions
Weights
Ballast / displacement
27.9%
Rig & sail area
Rig
Masthead Sloop
Ratios
SA / displacement
19.5
Displacement / length
199.0
Comfort ratio
13.9
Capsize screening
2.30
Hull speed
5.8 kn
Pounds / inch immersion
542
Hull
Hull type
Fin w/transom hung rudder
Construction
Fiberglass
Production
Years built
First built 1976
Designer
Sparkman, Stephens
Builder
Alpa

Boats like this, on the water

Nobody has filmed this one — but these are close.

Comparable boats the fleet has on camera: same type, within a quarter of her length. Open the boat, or watch the video — a timestamp means she only appears in passing.

Halcyon 236.93 mSame hull family0.4 m longerA triple-keeled masthead sloop by Alan H. Buchanan, offering shallow-draft versatility based on the earlier Crystal 23
J Boats Tillotson Pearson J/247.32 mSame hull family0.8 m longerA legendary Rodney Johnstone design that defined the modern one-design racer with its high sail-area-to-displacement ratio
Marieholm Boats S-206.00 mSame hull family0.5 m shorterA short-run 1970s fractional sloop with a fin keel and transom-hung rudder, designed for coastal agility
Sirius 7277.27 mSame hull family0.8 m longerA development of the Sirius 24, this fractional sloop features a fin keel with skeg-mounted rudder for balanced handling
Jeanneau Sun Odyssey 24.27.30 mSame hull family0.8 m longerA Jacques Fauroux-designed fractional sloop built for coastal cruising with a stable fin-and-bulb keel
Cal 257.62 mSame hull family1.1 m longerA flush-deck masthead sloop featuring a pop-top companionway that became one of the most popular models in the fleet

The family

Boats like this

Nearby designs by size, type, and era — worth a look alongside her.

Keep looking

Nothing filmed of this one yet

Two ways to keep looking — both search what the fleet has actually recorded.

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